Were Rhosyfelin fragments used as tools?

I was chasing around for information on lithics and stone tools used in the Neolithic, and I came across this piece on Mike Pitts's blog from the year 2011.  Interesting.  He suggests here that rhyolite is rather useful for the making of tools of various kinds -- especially for cutting things -- and that maybe some of the Rhosyfelin rhyolite found in the Stonehenge debitage is associated with tool-making either in conjunction with orthostat destruction or with tool manufacture at Rhosyfelin itself.  This is something I have suggested before, many times, on this blog.  The illustration above comes from his blog, and presumably shows various rhyolite chips and flakes up to 5 cm long.

Pitts on rhyolite chips and flakes...

https://mikepitts.wordpress.com/2011/12/20/bluestones-on-news-at-ten/

"One of the distinctive features of the rhyolitic rocks is that they are flinty – they have a good conchoidal fracture. That makes them relatively easy to break up, if they are standing as monoliths at Stonehenge. But it also makes them pretty good for making tools, or portable artefacts of some kind. There are plenty of flaked bluestone “tools” in museum collections from Stonehenge (some of them from my own dig, as illustrated above, from my PPS report). Which of these are made from debris created when stones were dressed on site? Which are made from broken up megaliths? And which were made in Wales and brought to Stonehenge by people visiting, perhaps on a pilgrimage of some kind? Clearly the distinction has important implications for how we understand Stonehenge.

These are questions that future research can answer, through excavation in Wales and at Stonehenge and study of the debris – that we can do this is a reflection of the quality and utility of the new research. Ixer and Bevins identified five groups of rock amongst the rhyolitic pieces they studied, of which three (by far the bulk of all they saw) they have matched to the Pont Saeson outcrops. There is one buried stump at Stonehenge (stone 32e) that they say could well be from Pont Saeson (to be confirmed), but the four standing rhyolitic stones are different. One of the latter (stone 48) belongs to one of the two very rare classes that Ixer and Bevins identified, which have yet to be matched to a source. One way excavation at Stonehenge would help us, is in allowing modern identification of the stumps and other bits of megaliths at the site."

Wiki:  In lithic stone tools, conchoidal fractures form the basis of flint knapping, since the shape of the broken surface is controlled only by the stresses applied, and not by some preferred orientation of the material. This property also makes such fractures useful in engineering, since they provide a permanent record of the stress state at the time of failure. As conchoidal fractures can be produced only by mechanical impact, rather than frost cracking for example, they can be a useful method of differentiating prehistoric stone tools from natural stones. .............  A swelling appears at the point of impact called the bulb of percussion. Shock waves emanating outwards from this point leave their mark on the stone as ripples. Other conchoidal features include small fissures emanating from the bulb of percussion.

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This is all a nice idea, but it's worth making the point that there are no -- or very few -- conchoidal fractures in the Rhosyfelin foliated rhyolites.   The fractures are not curved and crescentic, but tend towards being straight and flat.  Just take a look at this photo of rather typical splintered or shattered fragments from the rockfall debris on the flank of the crag:

In my discussions with visitors to Rhosyfelin we have had many duscussions about whether fresh flakes and slivers, either picked up or knocked off the edges of exposed rock surfaces, or even knocked off orthostats at Stonehenge, would make desirable and valuable tools for cutting flesh, skinning animals etc.  Some of us think the foliated rhyolite is rather soft to be used for long-lasting tools, and others disagree.  Edges are certainly very sharp indeed.  Maybe such flakes were so abundant that they could be treated as disposable items, rather like plastic knives are used as cheap substitutes for knives made of Sheffield steel?

This is an interesting dilemma, which maybe needs some input from lithics experts.  What do others think?